Abstract: Actions of bicategories arise as categorification of actions of categories.They appear in a variety of different contexts in mathematics, from Moerdijk-sclassification of regular Lie groupoids in foliation theory, to Waldmann-s workon deformation quantization. For any such action we introduce an actionbicategory, together with a canonical projection strict 2-functor to thebicategory which acts. When the bicategory is a bigroupoid, we can impose theadditional condition that action is principal in bicategorical sense, givingrise to a bigroupoid 2-torsor. In that case, the Duskin nerve of the canonicalprojection is precisely the Duskin-Glenn simplicial 2-torsor.